A common power supply includes a filter rectification unit, a boost unit (including a conventional power factor correction unit having a boost function) and a switchable power conversion unit. These elements are mostly integrated onto a circuit board. The filter rectification unit of the power supply connects to a power source to obtain an input power first, and then the boost unit (also including a conventional power factor correction unit) modulates the voltage of the input power to generate a boost power. Finally, the boost power is converted into an output power by the power conversion unit to drive at least one load.
In general, to ensure the quality of the supplied power, the output power generated by the power conversion unit must be further processed by a rectification filter circuit in order to serve as a DC power to drive computer components. This rectification filter circuit is commonly arranged at a secondary side of the power conversion unit and mainly includes an inductor and a capacitor. The rectified and filtered output power is then outputted to a rear-end computer component through at least one module slot. The rear end of the rectification filter circuit on a motherboard sequentially includes a power output circuit and a ground circuit to which the module slot is respectively connected. The power output circuit obtains the output power, whereas the ground circuit allows the module slot to be grounded. However, the current of the ground circuit will flow back to the front-end circuit of the motherboard because its flowing path passes through the power output circuit. Thus the reflux current in the ground circuit is lost to further reduce the amount of the reflux current.